Method of making a cooled rocket nozzle



Jan. 25, 1966 F. J. REcHlN ETAI.

METHOD OF MAKING A COOLED ROCKET NOZZLE 2 Sheets-Sheet 1 Filed April 18, 1961 Jan. 25, 1966 F. J. REcHlN ETAL METHOD OF MAKING A COOLED ROCKET NOZZLE Filed April 18, 1961 2 Sheets-Sheet 2 M lac/L An EYS INVENTORS enczLsJFefzn y BYEa/I/morz United States Patent O of Ohio Filed Apr. 18, 1961, Ser. No. 103,748 4 Claims. (Cl. 29-157) This invention relates to the fabrication of one piece rocket motor nozzles having internal passages for flow of a coolant through the nozzle wall.

Heretofore, the operating life a non-cooled reaction motor gas discharge nozzles was quite short because of the requirement that the nozzle be constructed of materials having high temperature resistance. The nozzle wall thickness of such materials added considerably to the weight of the vehicle with which the nozzle was employed. With some non-cooled nozzles constructed of certain refractory materials, the allowable working stresses which the material of construction could withstand was considerably reduced since the thickness of the walls was reduced in order to reduce weight. Regeneratively cooled nozzles required return lines for the cooling medium and involved a complicated fabrication problem. The weight therefore of such nozzles was increased considerably.

By employment of the present invention wherein a plurality of open ended coolant fiow passages are formed in the nozzle wall extending to the edge of the nozzle exit portion, we have substantially overcome the problems and difficulties of the prior art and provide a one piece reaction motor nozzle having a plurality of open ended internal passages formed in the nozzle wall for coolant iow.

It is therefore an object of the present invention to provide an improved method for fabricating reaction motor gas discharge nozzles from one piece billets.

Another object of the present invention is to provide an improved method for fabricating a one piece reaction motor nozzle from a single billet having a plurality of annularly arranged liow passages in the nozzle wall thereof.

It is another object of the present invention to provide an improved method for forming reaction motor nozzles wherein cooling passages are formed in the one piece billet before the billet is shaped to final nozzle form.

These and other objects, features and advantages of the present invention will become more apparent from a careful consideration of the following detailed description, when considered in conjunction with the accompanying drawing, illustrating preferred embodiments of the present invention, and wherein like reference numerals and characters refer to like and corresponding parts throughout the several views.

On the drawings:

FIGURE l is a view in longitudinal section of a short cylindrical billet having passages therein which is formed into a reaction motor nozzle.

FIGURE 2 is a view in cross-section taken along lines Il-II of FIGURE l.

FIGURE 3 is a view in longitudinal section illustrating the billet of FIGURE l after the extrusion thereof.

FIGURE 4 is a view in longitudinal section illustrating the billet of FIGURE 3 with one end upset.

FIGURE 5 is a view in longitudinal section of the billet of FIGURE 4 after the upset end thereof is out-turned.

FIGURE 6 is a view of the billet of FIGURE 5 after the nozzle exit portion has been fiared into final form.

FIGURE 7 is an enlarged fragmentary view taken along lines VII-VII of FIGURE 6.

FIGURE 8 is a View in longitudinal section of an alternative embodiment of the present invention.

FIGURE 9 is a view in partial elevation taken along lines IX-IX of FIGURE 8.

As shown on the drawings:

Briefly stated, the present invention involves the formation of gas discharge nozzles for reaction motors propelling and and space borne vehicles, such as missiles, rockets, satellites and the like.

The method of manufacturing the one piece reaction motor nozzles from a one piece billet is shown in FIG- URES 1 6.

As appears in FIGURE l, a billet, generally indicated by the numeral 11 of sufficient volume to provide the final form reaction nozzle is formed by extrusion or otherwise from a metal, such as 321 stainless steel or other refractory material. The short, lcylindrical billet 11 is axially bored as at 12 to provide the main flow path for the exhaust gases through the nozzle. A plurality of annularly arranged passages 13 of smaller diameter than the axial bore 12 is formed in the billet 11. These passages 13 are provided for flowing a -coolant medium, such as air, to cool the reaction motor nozzle.

The passages 13 are then lled with a material that has a hot plasticity characteristic similar to the base metal of the billet 11 but which has chemically dissimilar properties to permit removing of the material from the passages 13 by an oxidizing acid bath subsequently. Such materials are well know in the art.

As appears in FIGURE 3, the billet 11 having the core material 14 in the passages 13 is next extruded to provide an elongated cylinder thereby reducing the wall thickness of the billet 11 and the size of the passages 13.

Next, the cylinder of FIGURE 3 is subjected to a third operation wherein the nozzle entrance portion which is to communicate with the reaction chamber of the reaction motor is upset by conventional means to provide a tapered inner wall 16 and outer wall 17. It will be appreciated that the passages i3 in the upset portion of the cylinder 11 are now in angled relationship as at 1S with the passages formed in the portion of the nozzle which was not upset.

Thereafter, as appears in FIGURE 5, the upset portion of the nozzle is subiected to an additional upsetting, forging or flow turning operation to provide an annular flange I9 and to complete tapering of the walls 16 and 17 to the final configuration required for smooth flow of the exhaust gases from the reaction motor through the nozzle entrance portion or chamber 2t). In this operation, the chord passages 13 are angled as at 29 by the flange forming operation with respect to the remainder of the flow passages.

The final upsetting, forging or liow turning operation, as appears in FIGURE 6, involves tapering the nozzle exit portion 21 to provide the divergent inner wall 23. In this final operation, the upsetting of the nozzle exit portion 21 is performed in such a manner as to decrease the diameter of the passages 13 progressively towards the outlet end 13a thereof prior to removal of the core material from the passages.

Thus, a reaction motor nozzle having cooling passages formed therein may be fabricated from a single billet having the passages initially formed therein. No further forming of the nozzle is required other than machining of the surfaces 25 of the nozzle entrance portion for attachment to the reaction motor and boring thereof as at 26 for receiving securing means, such as bolts.

The throat 27 may have bonded thereto or otherwise secured a throat insert 23 of refractory material to complete the DeLaval nozzle assembly.

In the alternative embodiment appearing in FIGURES 8 and 9, the throat 27 is upset in such a manner during the fabrication process as to define an integral arcuate throat 3 wall surface 30 thus eliminating the necessity for a throat insert 28 (FIGURE 6).

The core material in the passages 13 is removed by subjecting the finished nozzle to an acid bath, such as fuming nitric acid, which is non-reactive with the material of construction of the nozzle but does react with the core material for removal thereof.

The nozzle constructed in accordance with the present invention reduce the weight requirements for such nozzles by reducing the operating temperature by means of the cooling fluid owing through the passages 13 and thereby additionally raising the level of the allowable working stresses which the nozzle will withstand. The operating life of solid propellant nozzles and nonregeneratively cooled liquid propellant nozzles is extended.

At the end 33 of the nozzle exit portion 21 a high gas velocity occurs in accordance with the well known theories of thermodynamic flow through venturi nozzles. Because of this high exhaust gas velocity, a reduced static pressure exist in the discharge or nozzle exit portion. A pressure differential therefore is caused to exist across the passages 13 from the inlet 34 thereof to the outlets 13a. rIhe pressure differential across the passages is such as to cause ow to occur from the inlets 34 to the outlets 13a, thereby ingesting or aspirating cooling air at the inlets 34 of the passages 13. The rate and consequently quantity of cooling air flowing through the passages 13 to the outlets 13a thereof are determined as a function of the total cross-sectional area of the passages 13 and the exiting main stream of exhaust gases flowing through the nozzle exit portion 21 from the reaction motor.

Thus, the ratevof flow of the cooling air through passages 13 is controlled by the rate of flow of the exhaust gases through the nozzle exit portion 21 and vthereby means are providing for cooling the nozzle wall and thereby increasing its useful life. It will be observed that .the ow of the cooling medium through the passages 13 will occur while the nozzle is in an atmospheric environment and flow will be -assisted by the ow of entrained air surrounding the nozzle periphery. The cooling air iow,

.being dependent upon ow of the exhaust gases through ythe nozzle, will therefore flow when the nozzle is stationary or in flight and the rate of ow of the cooling air will respond proportionally to the rate of ow of the exhaust gases through the nozzle. Tapering of the passages 13 adjacent the outlets 13a thereof increases the rate of flow through the passages 13.

The air inducted through the openings 34 may be atmospheric air or, if desired, means may be provided for supplying stored air or cooling gas to the inlets 34.

Thus, the present invention lprovides simple methods for fabricating reaction motor nozzles from a one piece lbillet and may include the feature of air passages for cooling the nozzle.

Although various minor modifications of the present invention may become readily apparent to those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope `of our contribution to the art.

We claim:

1. The method of forming a one piece gas discharge nozzle for reaction motors comprising: boring a generally cylindrical billet to form a main gas discharge flow passage, forming a plurality of open-ended and axially aligned coolant flow passages of smaller diameter than the main ow passage in the wal-l of the billet, `coring the flow 'passages, divergingly tapering one end of the billet and main flow passage to form the nozzle exit portion and to Vangle the coolant flow passages adjacent the nozzle exit 'portion divergingly tapering the other end of the billet and main iiow passage to form the nozzle entrance portion and to angle the coolant flow passagesadjacent the nozzle entrance portion, and removing the core from the coolant ow passages.

2. The method of forming a one piece gas discharge nozzle for reaction motors comprising: boring a generally cylindrically billet to form a main gas discharge flow passage, forming a plurality of open-ended axially aligned coolant flow passages of smaller diameter than the main ow passage in the wall of the billet, coring the coolant flow passages, divergingly tapering one end of the billet and main How passage to form the nozzle entrance portion and to divergingly angle the coolant flow passages adjacent the nozzle entrance portion, divergingly tapering the other end of the billet and main ow passage to form the nozzle exit portion and throatportion and to divergingly angle the coolant flow passages adjacent the nozzle exit portion, tapering the flow passages adjacent the end of the nozzle exit portion remote from the throat portion, and removing the core from the coolant flow passages.

3. The method of forming a one piece gas discharge nozzle for reaction motors comprising: providing a main gas discharge How passage in a sleeve, forming a plurality of open-ended axially aligned coolant flow passages of smaller diameter than the main flow passage in the Wall of the sleeve, coring the coolant ow passages, elongating the sleeve and reducing the cross sectional area of the coolant flow passages, divergingly tapering one end of the sleeve and main fiow passage to form a nozzle entrance portion and to divergingly angle the coolant flow passages adjacent the nozzle entrance portion, divergingly tapering the other end of the sleeve and main flow passage to form a nozzle exit portion and to divergingly angle the coolant ow passages adjacent the nozzle exit portion, turning the end of the nozzle entrance portion to form a securing flange, and removing the core from the coolant flow passages.

4. The method of forming a one piece gas discharge nozzle for reaction motors comprising: providing a main gas discharge flow passage in a sleeve, forming at least one passage in the sleeve wall for owing a cooling medium of smaller diameter than the main ow passage therethrough, coring the cooling flow passage, elongating the sleeve, upsetting a portion of one end of the sleeve and main flow passage to form a divergingly tapered nozzle entrance portion and to angle the coolant flow passage adjacent the upset portion, upsetting a portion of the other end of the sleeve and main flow passage to form a diverging nozzle exit portion and throat portion while angling the coolant flow passage adjacent the nozzle exit portion, and removing the core.

References Cited by the Examiner UNlTED STATES PATENTS 1,644,157 10/1927 Smith 29--157 2,217,193 10/1940 Aronson 29-157 2,334,257 11/1943 Egger et al. 29--157 2,935,841 5/1960 Myers et al. 60--35.6 2,956,334 10/1960 Stewart 29-157 2,956,399 10/1960 Beighley 60-35.6 2,975,509 3/1961 Sejourrlet 29-156.8

WHITMORE A. WILTZ, Primary Examiner.

SAMUEL LEVINE, I-IYLAND BIZOT, Examiners. 

1. THE METHOF OF FORMING A ONE PIECE GAS DISCHARGE NOZZLE FOR REACTION MOTORS COMPRISING: BORING A GENERALLY CYLINDRICAL BILLET TO FORM A MAIN GAS DISCHARGE FLOW PASSAGE, FORMING A PLURALITY OF OPEN-ENDED AND AXIALLY ALIGNED COOLANT FLOW PASSAGES OF SMALLER DIAMETER THAN THE MAIN FLOW PASSAGE IN THE WALL OF THE BILLET, CORING THE FLOW PASSAGES, DIVERGINGLY TAPERING ONE END OF THE BILLET AND MAIN FLOW PASSAGE TO FORM THE NOZZLE EXIT PORTION AND TO ANGLE THE COOLANT FLOW PASSAGES ADJACENT THE NOZZLE EXIT PORTION 